2Foster, P., Tonkyn, A., & Wigglesworth, G. Measuring spoken language: A unit for all reasons [ J ]. Applied Linguistics ,2000,21:354 - 75.
3LaMer, B. & Nation, P. Vocabulary size and use: lexical richness in L2 written production [ J]. Applied Linguistics,1995,16:307 - 22.
4Meunier, F. Computer tools for interlanguage analysis: A critical approach [ A ]. In S. Granger ( ed. ) Learner English on computer. London and New York: Addison Wesley Longman, 1998.
5Ortega, L. & Iberri-Shea, G. Longitudinal research in second language acquisition: recent trends and future directions[ J ]. Annual Review of Applied Linguistics, 2005,25 : 26 -45.
6Wolfe-Quintero, K., Inagaki, S. & Kim, H. Y. Second Language Development in Writing: Measures of Fluency,Accuracy & Complexity [ M ]. Hawaii : Hawaii University Press, 1998.
